Yes. But it depends on what you are trying to accomplish if you need to or not.
If you are doing a 2 color stabilization, then you might try soaking (no vac) the wood in the lighter color for a day or two, then bake it, then sand of the outer crust, then put it under vac with the second color, then bake again.
If you are doing something like a corn cob that is really porous, then 2 cycles through may help.
If you are doing a normal piece of soft or punky wood, and only doing clear or one color, then 1 time through should be enough. If it isn't then you aren't pulling enough vacuum or the wood might not be a good one to stabilize (really hard or oily woods usually aren't the best for this process)-my opinion. Others will definitely differ.
Dave